WMOD00591

• Title: Investigations of Winter Storms over the Wasatch Plateau during the 1994 NOAA-Utah Field Research Program - Final Report
• Date: 7/1/1996
• State: UT
• Weather Modification - Doc Type: Report

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were fi\'e significant storm periods covering all or part of 11 different days. The five periods were:
A 26 Januarv 1994
B. 7 - 8 February 1994
C. 10 - 11 February 1994
D. 18 - 22 February 1994
E. 27 February 1994.
All periods had some differing synoptic characteristics, but the first three periods were generally
\\'armer than the last two, and several of the successful seeding experiments from the 1994 season
were conducted during the later colder period. The storm periods are described here in terms of the
synoptic conditions in which they evolved. Satellite imagery is used to describe the more general
cloud characteristics, and meteorological data plots from RRS are used to describe the local
conditions. Seeding episodes are shown \'\ith the meteorological data, and some discussion is given
about the quality of the experiments, based on availability of data from the various instruments and
other factors.

A. 26 January 1994 Storm Period
This storm represented a somewhat odd s}'noptic situation which lead to cloud development
m,'er the \Vasatch Plateau. Not all instrumentation was operational, but a seeding experiment was
conducted in a shallow and very lightly precipitating orographic cloud. On 25-26 January the upper
le\'el flow \vas split over the western U.S. At 700 mb a closed low gradually moved east-
southeastward across the Great Basin between 0500 (all times MST) 25 January and 1700 26
January. At the surtace a \'.~-eak low tracked through southern California. Nevada and Utah benveen
- -'

0500 and 1700 on 25 January, supported by a short wave moving through the southern branch of the
westerlies. By 0500 on 26 January both the surface low and the closed low at 700 mb were over
Colorado to the east and south of the Ctah research area.
A relatiyely large area of moisture <T - T d < 3 j accompanied the closed low across the Great
Basin, such that between 0500 and 1700 on 76 January the atmosphere at 700 mb was near
saturation. \Vinds near the center of the closed low were generally less than 5 m s-\ and shifted in
direction from southerly ahead of the low to north-northwesterly by 0500 on the 26 January with the

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